Motor drive for sewing machines



June 24 !924. 1,498,976

H. MAIMIN MOTOR DRIVE FOR SEWING MACHINES Filed Feb. 14, 1924 2 Sheets-Sheet 1 mvahToR B 7 m June 24 1924.

H. MAIMIN MOTOR DRIVE FOR SEWING MACHINES Filed Feb. 14 1924 2 Sheeis-Sheet 2 41 A ATTORNEYS W BY Ptenteel June 24, 5

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Application filed February 14, rate. ,S erial in. 692,815.

To all whom it may concern:

Be it known that I, HYMAN MAIMIN, a citizen of the United; States, residing at New York city, in the county of New York, State of New York, have invented certain new and useful Improvements in Motor Drives for Sewing Machines; and I do hereby declare the following to be a full, clear, and exact description of the invention, such aswill enable others skilled in the art to which it. appertains to make and use the same.

This invention relates to a variable speed motor drive for sewing machines.

In my copending, application, Serial No. 670,881; filed October 26,1923, I have described and claimed a variable speed motor drive for sewing machines, in which I employ a constantly running single speed motor having a truncated cone driving pulley, and'a loose pulley adjacent the small end of the cone and of substantially the same diameter. Variations in the sewing machine,

speed are obtained by moving the driving belt along the face of the cone. As the belt moves up the enlarging face of the cone not only does the gear ratio increase but the slippage of the belt decreases so that these two factors cooperate to speed up the machine. The present invention contemplates certain'improvements and refinements in the drive of the earlier application although utilizing the same principles of operation. These improvements relate to the gear-shifting mechanism, the brake which is applied when the belt is shifted onto the'loose pulley, and to the bracket which supports the motor, and its associated mechanism. These improvements will ]be described in connection with the accompanying drawings, illustrating certain preferred embodiments thereof, and more particularly pointed out in the appended claims. In these drawings, Fig. 1 is an elevation of the sewing machine equipped with the motor drive of the present invention, the driving beltbein shown passing about. the loose pulley and. in moperative position; Fig. 2 is an end elevation of the part shown in Fig. 1; Fig. 3 is a section through the two pulleys taken along line 3-3 of Fig. 2; Fig. a is a similar section-taken along line H of Fig. 2; and Fig. 5 is a section taken along line 5-' 5 of Fig. 2 through parts of the belt-shifting means but showing the pulleys in elevation.

In Fig. 1 a conventional sewing machine is shown mounted-upon a table 2, and provided with usual pulley 3 and handwheel 4.

The driving unit is situated immediately below the table and supported by a bracket 5, whichdepends from the lower face of the table and is bolted thereto. The motor 7 and the belt-shifting. and braking mechanism are carried by this bracket. I Power is transmitted to the machine by means of a tioned holes in the table.

Mounted upon the spindle 10 of the motor are two pulleys, a fast cone pulley 11 and a loose pulle 12 1 provided with ball bearings (see Figs. 3 and 4 The loose pulley is mounted ad acent the small end of the cone pulley and is of slightly less diameter than said small end, thus forming a small shoulder 13- at the place where the pulleys meet. This shoulder, however, is only slight and does not prevent the belt from being moved from the loose pulley onto the face of the cone pulley, but it does effectively prevent any unintended movement of the belt onto the cone pulley, and also serves to more effectively impart the initial driving power to the belt. As shown,- the loose pulley is provided with a slightly tapered or conical face.

Any tendency of the belt to slip off this pulley base of the cone pulley is provided with an annular seat 14 having a groove 15 in its middle. The cone pulley is also provided at its base with a flange 16 which makes it impossible for the belt to move 05 its seat on that s ide. The driving unit is positioned so that the base'14 of the cone pulley is in substantially the same plane as the pulley 3 on the sewing machine so that when; tlie sewing machine is being driven at maximum speed the belt 6 shall be run in a single plane. At this point, the belt is stretched to its maximum tautness.-

In order to move the belt from the loose pulle to the fast pulley and hold it upon any desired position of the cone, I have pro belt 6, which passes through suitably posiv lltl vided a novel and improved belt-shifting mechanism, which I shall now describe.

The bracket 5 is provided at one side with These elements are so positioned that the arm 23 is located on one side of the belt and the roller 26 and the arm 25 on the other, as shown most clearly in Fig. 4. The arm 23 and the roller 26 are also so' positioned relative to the belt that in both ex treme positions, there is a slight clearance between them and the belt. Upon the other end of the rod 20 extending beyond the plate 18 is mounted a bell crank lever 27 toone end of which is connected a rod 28 operated by treadle 29, while, the other end abuts against a collar 31 fixed upon the outer end of the upper rod 21. A second collar 32' is fixed upon this rod 21 beyond the other end of the plate 18 and serves to limit the inward movement of the belt-shifter frame. Encircling the fixed rod 20 and bearing against the plate 18 and crosshead 22, a compression coil spring 33 is located, which constantly urges the crosshead away from the plate 18.

In accordance with the present invention, I have also provided novel and improved means for braking the sewing machine when the belt has been moved-into inoperative position upon the loose pulley. A brake arm 34 is pivotally mounted-upon the outer and upturned end of the fixed rod 20. Gas end of this arm carries an arcuate brake shoe 35, designed to contact with the inner face of the rim of the loose pulley, as shown most clearly in Fig. 3. The other end of this arm is designed to contact through a set screw 36 with the outer end of the belt-shifting frame, as also shown most clearly in Fig. 3.

The operation of the drive may be described and briefly reviewed as follows The motor is constantly running so that the fast pulley 11 is constantly rotated at uniform speed. Starting from the position of restshown in Fig. '1 with the belt encircling the loose pulley, the operator bears upon the treadle, and through the connection rod 28 and the bell crank lever 2'? moves the beltshifting frame to the left, as shown in Fig. 1. This movement brings the roller 26 into contact with the belt and moves it into contact with the shoulder 13 on the pulley essors tion, there is considerable slippage and only a very slow motion is imparted to the sewing machine. If higher speeds are desired, the operator presses the treadle farther down and moves the belt along the encircling face of the cone pulley; thus decreasing the slippage at the same time that the gear ratio is increased. At full speed the belt rides upon the grooved base of'the fast pulley. To decrease the speed or stop the machine, pressure on the treadle is relieved and the spring 33 immediately moves the belt-shifting frame toward the right; this movement bringing the arm 23 into contact with the belt and forcing it from the seat 14. In initiating the driving movement should the belt tend to lag and not respond to the pressure of roller 26 around the entire contacting periphery of the pulley, the arm 27) which immediately follows the roller 26 gives the lagging belt the necessary pressure to force it into alignment. Movement of the belt-shifting frame into its extreme right hand position with the belt wholly upon the loose pulley brings the frame into contact with the set screw 36 and automatically applies the brake. The loose pulley is thus instantly held fixed and there is suiiicient frictional engagement between it and the belt, and the belt and the sewing machine pulley to prevent further rotation of the latter.

I claim:

1. In a motor drive for sewing machines, the combination of a motor having a fast and a loose pulley, means for shifting a driving belt from one pulley to the other, and means operated by the belt shifting means for braking the loose pulley when the belt is shifted thereupon.

2. In a motor drive for sewing machines,

upon the loose pulley.

3. In a motor drive for sewing machines, the combmatlon of a motor having 1. fast and a loose pulley, means for shifting a driving belt from one pulley to the other,

and a brake arm pivoted adjacent the loose pulley, having an arcuate shoe on one end adapted to contact with the inner face of the rim of the loose pulley, the other" end being actuated by the belt-shifting means to apply the brake when the belt is shifted upon the loose pulley.

4. In a motor drive for sewing machines, the combination of a motor having a fast and a loose pulley, means for shifting a driving belt from one pulley to the other, a

brake arm pivoted adjacent the loose pulley, having a shoe on one end adapted to contact with the loose pulley, the other end being actuated by the belt-shifting means to apply the brake when the belt is shifted upon the loose pulley, and a set screw in that end of the arm contacting with the beltshifting means. I

5. In a motor drive for sewing machines, the combination of a motor having a fast cone pulley and a loose pulley adjacent the small end of the cone pulley and of substantially the same diameter, and a belt shifter for shifting a driving belt from one pulley to the other comprising means for moving the driving belt up the inclined face of the cone pulley, and means spaced slightly beyond the moving means for preventing lagging of the belt.

6. In a motor drive for sewing machines, the combination of a motor having a fast cone pulley and a loose pulley adjacent the small end of the cone pulley and of substantially the same diameter, a belt shifter for shifting a driving belt from one pulley 'to the other comprising means for moving a driving belt up the inclined face of the cone pulley, means spaced slightly beyondthe moving means for preventing lagging of the belt, and means on the other side of the belt for moving the belt down the face of the cone. v I

7. In a motor drive for sewing machines, the combination of a motor having a fast cone pulley and a loose pulley adjacent the small end'of the cone pulley and of substantially.the same diameter, a belt shifter for shifting a driving belt from one pulley to the other comprising a roller for urging the belt up the inclined face of the cone pulley, an arm following the roller for preventing lagging' of the belt, and an arm on the other side of the belt for moving the belt down the face of the cone pulley, the two arms and the roller being mounted upon a sliding frame.

8. A support for the motor driveof claim 7, comprising a bracket designed to depend from the under face of the sewing machine table and provided with a housing for the sliding belt-shifter frame.

In testimony whereof I aflix my signature.

MAIMIN. 

